Note to husbands who need excuses to play the guitar with their buddies and to parents justifying the cost of their children’s piano lessons: A new study from Northwestern University in Evanston says lifelong playing of musical instruments has a positive impact on the brain.

“Our neural timing slows as we age; we knew that,” said Nina Kraus, a neuroscientist at Northwestern and principal investigator of its Auditory Neuroscience Laboratory. “Hearing what your spouse says when you’re in a noisy restaurant, for example, is harder when you’re older. But this study shows that musicians are faster at processing noise than non-musicians are. This shows us there is a biological impact of musical training.”

It makes sense, said Kraus.

“A musician has to be constantly picking out sounds from others,” she said. “Just as we lift weights to build our biceps, playing music makes our nervous systems more efficient.”

The study included 87 participants — younger (18 to 32) and older (45 to 65), musicians and nonmusicians. The musicians were not all professional, but they played their instruments at least three times a week into adulthood.

“I watched a movie with captions to keep me awake while electrodes on my head measured my reaction to sounds I heard through headphones,” said study participant Rick Wunder, 60, from Evanston.

Wunder is a retired systems analyst who has played the trombone since he was a child and now plays in a community symphony and in several brass quartets.

The electrodes measured how Wunder’s nervous system responded to the sounds he heard.

“We’re talking milliseconds of time,” said Kraus. “It’s very objective; the mood of the participant didn’t matter.”

“The results are very interesting, I think,” said Wunder. “When I’m with other people my age in a loud place like a sports bar, I can tell they don’t necessarily hear what I say, while I still can.”

In the study’s chart that compares sound to neural responses among musicians, the two wavy lines are in sync. But the nonmusicians’ chart looks like confetti (the neural responses) thrown at a wavy line (the sounds the participants heard).

The study is affecting education policymaking, said Kraus.

“We’ve been pleased to hear from educators who have used our website (soc.northwestern.edu/brainvolts/slideshows/music) to argue for funding for continuation of musical education,” she said. “We’re giving them biological evidence that, yes, continued musical education matters.”

In addition to the affects of aging, musical training affects daily activities of young people such as hearing a teacher in a noisy classroom or even simple conversation, explained Kraus.

“As we’re talking, your brain has to remember what you just said,” she said.

The study will be published in a 2012 edition of the journal Neurobiology of Aging.